Technical Field
The present invention relates, in particular, to an apparatus that detects a vehicle-lane boundary line, such as a white line, based on a road surface image capturing a road surface ahead of a vehicle, and a method thereof.
Background Art
A vehicle-lane boundary line detection apparatus has been proposed in the past that detects a boundary line of a vehicle lane (hereinafter, a vehicle-lane boundary line), such as a white line, based on a road surface image capturing a road surface ahead of a vehicle. An apparatus such as this detects the vehicle-lane boundary line from a road surface image. Therefore, when the road surface is covered by snow, the white line or the like on the road surface does not appear in the road surface image. The vehicle-lane boundary line cannot be appropriately detected.
Therefore, as described in PTL 1, an apparatus is proposed that determines a degree of variation in the disposition of a detected vehicle-lane boundary line (lane marker). When the degree of variation is a predetermined threshold or higher, the apparatus determines that an inhibiting factor that reduces recognition accuracy of the vehicle-lane boundary line is present. This apparatus is configured to determine that an inhibiting factor that reduces recognition accuracy of the vehicle-lane boundary line is present when variations in the position of the vehicle-lane boundary line occur due to snow.
PTL 1 JP-A-2009-271908
When a rut is formed on a snow-covered road, the boundary portion between the snow and the road surface may be linear (for example, refer to FIG. 4, described hereafter). In the above-described apparatus in PTL 1, when a boundary line is formed linearly in this way, variations do not occur in the disposition of the detected lane marker. Therefore, an inhibiting factor is not determined as being present. An erroneous detection that the lane marker is correct may be made.